1. Field of the Invention
The present invention relates to tyrosinase-inhibiting agents and further specifically relates to tyrosinase-inhibiting agents containing extracts or fractions prepared from Gardenia fruit, Sophora root, and Rosa fruit as the active ingredients. The tyrosinase-inhibiting agents of this invention may be used for improving the skin color and the like.
2. Description of the Related Art
Tyrosine, which is a type of amino acid, is converted by the action of tyrosinase enzyme into melanin, a black-brown to red-brown pigment, which is the cause of skin blemishes and spots. In order to prevent the production of melanin under the action of tyrosinase, various compounds have been used or proposed to inhibit the activity of tyrosinase in the fields of cosmetics and foods.
Representative examples of such compounds are ascorbic acid, sulfur compounds, hydroquinone, kojic acid, and natural plant extracts.
Ascorbic acid suffers from stability problems in the presence of moisture, while sulfur compounds have odor problems. Hydroquinone has a very high degree of efficacy, but has the shortcoming being highly toxic. Kojic acid and natural plant extracts have a high degree of safety but have weak tyrosinase-inhibiting activity, and in addition plant extracts often have odor and color problems.
In the recent years in view of the heightened interest by the society in cosmetics with a high degree of safety in promoting health, there is a need for tyrosinase-inhibiting agents which inhibit melanin production, which could be widely used in cosmetics, which are derived from natural products of high degree of safety, and which do not adversely affect the quality of the final product from the standpoint of taste or odor.
Japanese Patent Application Publications Showa 50-135236, Showa 60-104005, Showa 64-26507, Heisei 3-193712, Heisei 6-65045, Heisei 6-128143, Heisei 6-336418, Heisei 8-99859, Heisei 6-336418 and Heisei 8-99859 describe extracts of Gardenia, Sophora and Rosa which have tyrosinase-inhibiting activity.
Japanese Patent Application Publications Heisei 3-157334, Heisei 7-61915, Heisei 7-25762, and Heisei 5-139950 describe the uses of extracts of Gardenia, Rosa, or Sophora plants in the prevention and treatment of skin blemishes.
Japanese Patent Application Publications Heisei 10-279462, Heisei 10-279460, Heisei 10-265322, Heisei 10-265321, Heisei 10-182404, Heisei 10-330217 describe the use of Rosa or Sophora plant extracts as tyrosinase-inhibiting agents.
However, none of these show effective efficacy as a tyrosinase-inhibiting agent.